Proteins are frequently being used therapeutically in treating various physical conditions. Examples of such proteins are Interferon-alpha (IFN-alpha), erythropoietin (EPO), granulocyte-colony stimulating factor (G-CSF), insulin, granulocyte-macrophage-colony stimulating factor (GM-CSF) and others. Even though these proteins are useful, the dosing of these proteins is very often difficult because they have a short blood serum half-life.
For example, IFN-alpha is generally administered either by intramuscular, subcutaneous or intralesional injection usually in hospital or clinical settings. IFN-alpha has a serum half-live of 2-6 hours when injected subcutaneously or minutes when injected intravenously, and characteristically shows a "burst" or a "pulse" (i.e., a rapid blood serum level rise followed by a rapid blood serum level clearance) profile when blood levels are measured over time. Thus frequent administration of doses of the protein must be made to maintain a therapeutically effective blood serum concentration of the drug. There are clinical situations there is a need to develop an IFN-alpha formulation in which the protein is continuously released into the blood stream so that the serum concentration of the protein reaches a plateau and remains at that level for a period of time. This is known as a controlled release formulation.
Examples of pharmaceutically acceptable vegetable oils are sesame, peanut, saffron, and canola oils.